221 lines
8.1 KiB
C++
221 lines
8.1 KiB
C++
/** @file DIfElseSsm.hpp
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*
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* @author Roland Conybeare, Jul 2025
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**/
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#pragma once
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#include <xo/expression2/DIfElseExpr.hpp>
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#include "ParserStateMachine.hpp"
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#include "syntaxstatetype.hpp"
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#include <xo/expression2/detail/IExpression_DIfElseExpr.hpp>
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#include <xo/expression2/DIfElseExpr.hpp>
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#include <xo/facet/obj.hpp>
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//#include "exprstate.hpp"
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//#include "xo/indentlog/print/ppdetail_atomic.hpp"
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namespace xo {
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namespace scm {
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/**
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* if test-expr then then-expr else else-expr ;
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* ^ ^ ^ ^ ^ ^ ^
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* | | | | | | |
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* | if_1 if_2 if_3 if_4 if_5 if_6
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* if_0
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*
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* if_0 --on_if_token()--> if_1
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* if_1 --on_expr()--> if_2
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* if_2 --on_then_token()--> if_3
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* if_3 --on_expr()--> if_4
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* if_4 --on_else_token()--> if_5
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* --on_semicolon_token()--> (done)
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* if_5 --on_expr()-->if_6
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* if_6 --on_semicolon_token()--> (done)
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**/
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enum class ifexprstatetype {
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invalid = -1,
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if_0,
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if_1,
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if_2,
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if_3,
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if_4,
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if_5,
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if_6,
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N,
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};
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extern const char * ifexprstatetype_descr(ifexprstatetype x);
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std::ostream &
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operator<<(std::ostream & os, ifexprstatetype x);
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/** @class DIfElseSsm
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* @brief syntax state machine for parsing a conditional expression
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**/
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class DIfElseSsm {
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public:
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using AAllocator = xo::mm::AAllocator;
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using DArena = xo::mm::DArena;
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using TypeDescr = xo::reflect::TypeDescr;
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using ppindentinfo = xo::print::ppindentinfo;
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public:
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/** @defgroup scm-ifelsessm-expression-ctors constructors **/
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///@{
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explicit DIfElseSsm(DIfElseExpr * ifelse_expr);
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#ifdef NOT_YET
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/** create instance using memory from @p parser_mm
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* with initial scaffold @p ifelse_expr
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**/
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static obj<AExpression,DIfElseSsm> make(DArena & parser_mm,
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DIfElseExpr * ifelse_expr);
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#endif
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/** create instance using memory from @p parser_mm
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* with initial scaffold @p ifelse_expr.
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**/
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static DIfElseSsm * _make(DArena & parser_mm,
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DIfElseExpr * ifelse_expr);
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/** start nested parser for an if-else expression
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* on top of parser state machine @p p_psm.
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* Use @p parser_mm to allocate syntax state machines
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* (i.e. temporary memory needed only during parsing)
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* Use @p expr_mm to allocate expressions.
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**/
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static void start(DArena & parser_mm,
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obj<AAllocator> expr_mm,
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ParserStateMachine * p_psm);
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///@}
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/** @defgroup scm-ifelsessm-expression-methods general methods **/
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///@{
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/** operate state machine on if-token input @p tk,
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* with overall parser state in @p p_psm
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**/
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void on_if_token(const Token & tk,
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ParserStateMachine * p_psm);
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/** operate state machine on then-token input @p tk,
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* with overall parser state in @p p_psm
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**/
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void on_then_token(const Token & tk,
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ParserStateMachine * p_psm);
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/** operate state machine on else-token input @p tk,
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* with overall parser state in @p p_psm
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**/
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void on_else_token(const Token & tk,
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ParserStateMachine * p_psm);
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/** victory: report completed @ref if_expr_ to parent ssm,
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* after removing this ssm from parser stack
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**/
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void finish_and_continue(ParserStateMachine * p_psm);
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///@}
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/** @defgroup scm-ifelsessm-expression-facet expression facet methods **/
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///@{
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/** identifies this state machine **/
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syntaxstatetype ssm_type() const noexcept;
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/** text describing expected/allowed input to this ssm in current state.
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* Intended to drive error messages
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**/
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std::string_view get_expect_str() const noexcept;
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/** operate state machine for this syntax on incoming token @p tk
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* with overall parser state in @p p_psm
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**/
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void on_token(const Token & tk,
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ParserStateMachine * p_psm);
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/** operate state machine for this syntax on incoming semicolon token @p tk
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* with overall parser state in @p p_psm
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**/
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void on_semicolon_token(const Token & tk,
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ParserStateMachine * p_psm);
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/** update state for this syntax after parsing an expression @p expr,
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* overall parser state in @p p_psm.
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**/
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void on_parsed_expression(obj<AExpression> expr,
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ParserStateMachine * p_psm);
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/** update state for this syntax after parsing a type description @p td;
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* overall parser state in @p p_psm
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**/
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void on_parsed_typedescr(TypeDescr td,
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ParserStateMachine * p_psm);
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/** update state for this syntax after parsing an expression @p expr,
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* followed by semicolon,
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* with overall parser state in @p p_psm.
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**/
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void on_parsed_expression_with_semicolon(obj<AExpression> expr,
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ParserStateMachine * p_psm);
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/** update state for this syntax after parsing a symbol @p sym,
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* with overall parser state in @p p_psm
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**/
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void on_parsed_symbol(std::string_view sym,
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ParserStateMachine * p_psm);
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///@}
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/** @defgroup scm-ifelsessm-printable-facet printable facet methods **/
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///@{
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bool pretty(const ppindentinfo & ppii) const;
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///@}
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#ifdef NOT_YET
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// ----- inherited from exprstate -----
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virtual const char * get_expect_str() const override;
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virtual void on_if_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_then_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_else_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_semicolon_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_rightbrace_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_expr(bp<Expression> expr,
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parserstatemachine * p_psm) override;
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virtual void on_expr_with_semicolon(bp<Expression> expr,
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parserstatemachine * p_psm) override;
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virtual void print(std::ostream & os) const override;
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#endif
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private:
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#ifdef NOT_YET
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static std::unique_ptr<if_else_xs> make();
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/** exit this exprstate,
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* and deliver @ref if_expr_ to parent exprstate
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**/
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void finish_and_continue(parserstatemachine * p_psm);
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#endif
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private:
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ifexprstatetype ifstate_ = ifexprstatetype::invalid;
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/** scaffold ifelse-expression here.
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* This will eventually be the output of this ssm
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**/
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obj<AExpression,DIfElseExpr> if_expr_;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end DIfElseSsm.hpp */
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